The overall purpose of this grant is to elucidate the cytological mechanisms underlying the manufacture of the specific products that characterize differentiation. In the current year, we will concentrate on the role of the extracellular matrix, especially collagen, in embryonic induction. We will test the effects of different collagens and glycosaminoglycans on corneal differentiation in vitro. We also plan to study the role of the Golgi complex in collagen secretion, using ferritin labeled antibodies and electron microscopy, and to study the relation of collagen to the cell membrane using freeze-cleave and scanning electron microscopy.